In recent years, semiconductor light emitting components have gradually replaced traditional lighting devices. The light emitting diode (LED) has a lot of advantages, such as small volume, quick response time, long service life, not easily attenuated, rigid outer casing, vibration-resistant, ability to emit different colors of light (including invisible light), allowing oriented-design, low voltage, low current, low conversion loss, low thermal radiation, easily mass-producible, environmental friendly, etc.
A conventional LED includes an LED dice encapsulated in a lamp-shaped package. A pair of leads is extended from the LED dice through the package for electrically connecting to external power sources. To use the LED, the pair of leads is respectively soldered to a positive conductor and a negative conductor, so that an electric current can be supplied to the LED dice via the leads for the LED to emit light. Since the lamp-shaped LED has a relatively large volume, a surface mounted LED having relatively small volume has been developed in response to the future trend of small-scale packaging and automated production of LEDs.
While the LED has a lot of advantages, it has the disadvantage of insufficient brightness due to its characteristics of low voltage and low current. Generally, to increase the brightness of the LED, a plurality of LEDs are combined or serially connected to form a light set or a light string for use.